With the advent of the advanced semiconductor technology, sophisticated image processing technology, growth in high speed network, and further, widespread use of digital video cameras, digital still cameras and the digital sound recording/reproducing technology in recent years, the number of multimedia files requiring management has been increasing. In a case where many of multimedia files are to be managed, a need for some contrivance arises in order to specify contents of a multimedia file. The most popular way adopted for the purpose is to give a title that expresses contents of the multimedia file to the multimedia file itself. For example, a title “Birthday Party for My Wife in '95” is the case.
Furthermore, a case exists such that a comment on a file can be attached to the file as an attribute or additional information thereof in some of operating systems (OS) for a personal computer. On such an operating system, information expressing contents of a file can be further attached to the file attribute or additional information in addition to a title of the file. Generally speaking, while there is a limitation on a length of a title, a length of information which can be attached to a file as an attribute thereof is longer than the limitation; therefore, more detailed information can be provided.
When information that expresses contents of a multimedia file as a title or an attribute is attached to the multimedia, a person responsible for linking the title or information would be able to identify a desired file among many of files. Others, however, will have difficulty in correctly knowing contents of a multimedia file based solely on a title or information attached to the multimedia file. Especially, it will be more difficult to find a multimedia file with desired contents among many files based solely on a title or such information thereof. Consequently, it has been a common practice to investigate contents of multimedia files one by one to identify the contents thereof to find out a desired multimedia file.
A technique to solve such a problem is disclosed in Japanese Patent Laying-Open No. 6-195880(1994). The technique disclosed in the publication relates to an image file including, for example, an intra-coded picture (referred to as I picture) as defined in MPEG (Moving Picture coding Experts Group). An I picture is obtained by encoding one frame of an image to be encoded, regarding it as a still picture. That is, the I picture is a frame image encoded without using interframe prediction. Hence, the original frame can be decoded without referring to another picture.
According to this prior art technique, one or a plurality of I frames (frame constituted of an I picture) in each image file are selected in advance, selected encoded data itself or position information of the selected encoded data in the image file is extracted and the data or the information is linked to the head end of the image file as a management heading. Thus, frames expressed with encoded datas are restored based on management headings at the heads of many image files and displayed into a list.
FIG. 1 shows a file structure that was adopted in the prior art. Referring to FIG. 1, an image file 30 includes: a management heading 32 stored on a recording medium such as a hard disk; and a moving picture data 34 consisting of I frames cyclically placed and a plurality of P frames inserted between I frames. The P frame is a frame constituted of a P picture (predictive-coded picture) obtained by encoding based on prediction from the previous I frame of the frame of interest. The management heading 32 contains information specifying contents of a selected I frame itself or a position of the selected I frame.
FIG. 2 shows a system configuration for outputting a prior art image file 30. In this system, position information of a selected I frame is stored in the management heading 32. Referring to FIG. 2, a prior art system 40 includes: a title frame specifying section 42 for specifying one or more I frames representing contents of each of image files; a title frame position analyzing section 44 for analyzing a position of the one or more I frames in each of image files; and a title frame information generating section 46 for attaching information on the position of the one or more I frames analyzed by the title frame position analyzing section 44 to the head of the each of image files as a management heading 32. Note that the title frame specifying section 42 specifies a default value (for example, an I frame at the leading place) as a title frame when no title frame is specified by a user.
In each of image files, some of I frames arranged cyclically are inevitably contained. Data in an I frame can be presented to a user in the form which the user can see without the help of data of another frame, similar to a still picture. Hence, any one can see an image of an I frame specified by the heading of an image file to identify contents of the image file and determine whether or not the image file is a desired one.
The technique shown in the publication of the above described Japanese Patent Laying-Open No. 6-195880(1994) has some of problems remaining to be solved. First of all, in this prior art technique, an I frame is limitedly selectable for a management heading. Even if a desired image is intended to be a heading image, the desired image cannot be a heading image when it is not of an I frame. Hence, in the prior art, a user cannot specify an arbitrarily selected frame as a heading image.
Furthermore, in a case where there is a file that expresses satisfactorily contents of a multimedia file as a different file from the contents of the multimedia file, a problem arises in that the different file cannot be specified as a title frame for a heading. In such a case, the different file can be desirably specified as a heading of the multimedia information file.
Besides, in a case where a title frame is a picture, it is more preferably used because of directly expressing the contents of a file if not only a still picture but also any moving picture can be specified.
The invention has been made in order to solve the above described problems and it is accordingly an object of the invention to provide a method and apparatus for managing a multimedia information file capable of specifying any frame as a title frame for use in a heading.
It is another object of the invention to provide a method and apparatus for managing a multimedia information file capable of specifying not only a still picture but also a moving picture as a heading image.
It is still another object of the invention to provide a method and apparatus for managing a multimedia information file capable of specifying any frame of any file including a file other than a multimedia information file to be processed as a heading image.
It is yet another object of the present invention to provide a method and apparatus for managing a multimedia information file capable of specifying not only a still picture but also a moving picture including a file other than a multimedia information file to be processed as a heading image.